μῆνιγξ
From LSJ
τὸ δὲ ποιεῖν ἄνευ νοῦ ἃ δοκεῖ καὶ σὺ ὁμολογεῖς κακὸν εἶναι: ἢ οὔ → but doing what one thinks fit without intelligence is—as you yourself admit, do you not?—an evil
English (LSJ)
ιγγος, ἡ,
A membrane, Hp.Carn.3; of the membrane of the eye, Emp.84.7 (pl.), Arist.GA781a20; drum of the ear, Id.Pr.961a38; esp. membrane enclosing the brain, dura mater, Hp.VC1, Arist. HA495a8, 514a17, Gal.2.708, etc.: in pl., ib.716, Q.S.5.327, 12.406. II scum on milk, Hsch.